1. Field of the Invention
The present invention relates generally to the field of plastic pipe fittings, and more particularly, is directed to an improved pipe fitting interlocking system including a novel interlocking and sealing construction.
2. Discussion of the Prior Art
In piping systems in general and in plastic piping systems in particular, it is the usual practice to provide sections of pipe in suitable increments, such as ten feet or twenty feet, for use in constructing a pipe line of a desired length. Each pipe section is fabricated to the designed internal diameter, usually by the extrusion process, and then has its ends worked as necessary to provide one bell or hub end and one spigot end of predetermined interrelating design to allow adjacent sections of pipe to be joined in a secure and leak proof manner.
In the usual manner, fittings such as ells, tees and wyes are employed in the piping system where design criteria require, and such fittings form the subject mater of the present invention. Fittings of smaller sizes are generally fabricated by molding for use with pipe sections of equal diameter. In the case of the large diameter work, the molding process cannot normally be economically employed and accordingly, it is the common practice to fabricate large diameter fittings of separate extruded plastic components and then to join the spearate parts together.
For example, when fabricating a wye fitting of twelve inch diameter, the central body in the configuration of the wye shape was first formed. At least some of the wye ends were then equipped with a separate bell or hub of suitable configuration to receive and seal against the spigot end of an interconnecting length of plastic pipe. In order to generate sufficient strength in each hub connection and to insure a leak proof fitting, a solvent weld or chemical junction was first formed between a hub and a free end of the wye central body. After all of the hubs were solvent welded in place, a second plastic weld or peripheral heat junction was then applied at each connected hub. These operations have proved to be time consuming, costly and subject to frequent quality control rejections. The pipe fitting interlocking system of the present invention seeks to overcome all of the problems inherent in the previous pipe fitting construction techniques.
As used herein, the term "large diameter" is defined to mean pipe and fitting diameters of ten inches, twelve inches and larger.